The invention is concerned with double-twist twister mechanisms, and it is applicable to twisters of the type disclosed in U.S. Pat. No. 4,158,282, issued June 19, 1979, to Jean-Paul Guertin et al.
This type of mechanism has a rotatable centered assembly which includes the rotating spindle, and a rotatable oblique assembly which rotates about an axis which is oblique to the rotational axis of the centered assembly. The opposite ends of the oblique assembly are rotatable, respectively, in the stationary main frame and in a spool carrier. The spool carrier is also rotatably connected to one end of the centered assembly, thereby immobilizing the spool carrier in space. The two assemblies overlap each other in the sense that each of them has at least one part crossing the other. They are coupled to each other by appropriate means, a suitable flexible coupling for this purpose being described in French Pat. No. 78 11 428, corresponding to U.S. Pat. No. 4,209,967, and which is incorporated herein by reference.
In such mechanisms, the connection of the oblique assembly to the spool carrier is quite important and critical, as the rotational axis of the oblique assembly where it connects to the spool carrier must be situated precisely in axial alignment with the rotational axis of the oblique assembly in the fixed frame. Such alignment is difficult to attain due to the accumulation of numerous tolerances involved in the installation process. One solution to this problem, described in the French Certificate of Addition 78 04 321 which corresponds to U.S. Pat. No. 4,158,282, is to enable the end of the centered assembly to slide in a ball-and-socket joint. A support is radially displaceable and can be fixed to the spool carrier after the mechanism is installed and functioning at a moderate speed. This permits self-alignment of the various parts, which thus makes it possible to take up the play of the various tolerances. Nevertheless, the assembling of these various pieces with narrow tolerances is a relatively slow and delicate process, as is the adjustment which has just been described. Furthermore, when deformation of the pieces occurs as a result of shocks, expansion or normal wear, it becomes necessary to carry out another such systematic adjustment.
The purpose of the present invention is to eliminate the preceding disadvantages by providing a structure which permits the oblique assembly to be connected to the spool carrier with a reduced number of pieces which are easy to install and which automatically effect a permanent self-alignment without undue vibrations at normal operating speeds.